diff --git a/pkgs/development/ocaml-modules/sedlex/default.nix b/pkgs/development/ocaml-modules/sedlex/default.nix
index cfe1938bf55b..27756fdcd26e 100644
--- a/pkgs/development/ocaml-modules/sedlex/default.nix
+++ b/pkgs/development/ocaml-modules/sedlex/default.nix
@@ -6,13 +6,19 @@
 , gen
 , ppxlib
 , uchar
+, ppx_expect
 }:
 
 let param =
-  if lib.versionAtLeast ppxlib.version "0.26.0" then {
-    version = "3.0";
-    sha256 = "sha256-+4ggynMznVfjviMBjXil8CXdMByq4kSmDz6P2PyEETA=";
-  } else {
+  if lib.versionAtLeast ppxlib.version "0.26.0" then
+    if lib.versionAtLeast ocaml.version "4.14" then {
+      version = "3.1";
+      sha256 = "sha256-qG8Wxd/ATwoogeKJDyt5gkGhP5Wvc0j0mMqcoVDkeq4=";
+    } else {
+      version = "3.0";
+      sha256 = "sha256-+4ggynMznVfjviMBjXil8CXdMByq4kSmDz6P2PyEETA=";
+    }
+  else {
     version = "2.5";
     sha256 = "sha256:062a5dvrzvb81l3a9phljrhxfw9nlb61q341q0a6xn65hll3z2wy";
   }
@@ -34,6 +40,7 @@ let
     url = "${baseUrl}/ucd/PropList.txt";
     sha256 = "sha256-4FwKKBHRE9rkq9gyiEGZo+qNGH7huHLYJAp4ipZUC/0=";
   };
+  atLeast31 = lib.versionAtLeast param.version "3.1";
 in
 buildDunePackage rec {
   pname = "sedlex";
@@ -49,7 +56,10 @@ buildDunePackage rec {
   };
 
   propagatedBuildInputs = [
-    gen uchar ppxlib
+    gen
+    ppxlib
+  ] ++ lib.optionals (!atLeast31) [
+    uchar
   ];
 
   preBuild = ''
@@ -59,6 +69,10 @@ buildDunePackage rec {
     ln -s ${PropList} src/generator/data/PropList.txt
   '';
 
+  checkInputs = lib.optionals atLeast31 [
+    ppx_expect
+  ];
+
   doCheck = true;
 
   dontStrip = true;